1. Field of the Invention
The present invention relates to a light emitting diode driving system, in particular with respect to a light emitting diode (LED) driving system with precise timing control dimming control used for driving light emitting diode elements and dimming method using the same.
2. Description of the Related Art
Because the energy crisis becomes more and more severe, LED, which is regarded as a high efficiency light source, has caused high attention. For example, white light LED has not only been commonly applied to backlight sources of consumer electronics, such as cell phone, PDA, LCD TV and so on, but also widely-used in public signal marks, industrial communication lighting system, car lamps, and fields of enormous normal industrial and civil lighting systems.
In addition, comparing with fluorescent lamp, energy saving lamp, high-pressure sodium lamp, dimming can be carried out easily in terms of LED light source; consequently, dimming function shall be added to various LED lamps. From smaller lighting equipment, such as light bulb to large one, LED's power source has to drive widespread diverse applications; additionally, the power source thereof still needs to support the Triac dimming which the traditional illumination lamps use, PWM dimming used by LED lighting and linear dimming by turning knob's variable resistance and so on and so forth.
Generally, the current LED switched dimming utilizes natural electrical discharge of capacitor to maintain the dimming status, and power source switcher is in off condition, it needs to use capacitor to supply power to flip-flop so as to maintain brightness count value; even though different voltage thresholds may be added to indicate the power source's condition, according to diverse situations of power source, switch leakage and elements of system, it may cause unstable operating status and imprecise timing dimming. As a result, it is a desire to accomplish a LED driving system with precise switched step dimming.